1. Field of the Invention
The present invention relates to an inkjet cartridge containing an ink absorber and a method for manufacturing the inkjet cartridge.
2. Description of the Related Art
FIG. 10 is a sectional side view illustrating an example of a known inkjet cartridge. This structure is described in Japanese Patent Laid-Open No. 3-248848 (corresponding to U.S. Pat. No. 5,237,342). In this structure, an inkjet recording head unit 105 includes an ink container and an inkjet recording head which are integrated with each other. More specifically, an ink container 101 which contains an ink absorber 102 for holding ink, a supply tube 104 for supplying ink to an ejection energy generating unit, and a recording head having a filter 103 disposed at an end of the supply tube 104 are integrated with each other.
This type of inkjet cartridge is replaced with another inkjet cartridge when it becomes impossible to eject ink. If the ink capacity of the inkjet cartridge is small, the inkjet cartridge must be frequently replaced, which is cumbersome for the user. The frequency of replacing the inkjet cartridge can be reduced by increasing the ink capacity thereof. In this case, the volume of the ink absorber and the volume of the ink-absorber container must be increased. However, if the size of the ink absorber and the size of the ink-absorber container are simply increased, severe conditions must be satisfied in the process of manufacturing the inkjet cartridge.
In general, the recording head is disposed on a bottom surface of the inkjet cartridge in the state in which the inkjet cartridge is mounted on a recording apparatus. The ink absorber is inserted through a top surface of the inkjet cartridge at the side opposite to the bottom surface. The ink is supplied to the recording head by pressing the ink absorber against the filter. Therefore, to increase the capacity of the inkjet cartridge without changing the installation area thereof in the recording apparatus, the space for holding ink in the ink-absorber container must be increased in the height direction thereof.
However, in such a case, the insertion stroke by which the ink absorber is inserted into the ink-absorber container increases. Therefore, it becomes difficult to press the ink absorber against the recording head disposed on the bottom surface. If the ink absorber cannot be tightly pressed against the filter, there is a risk that air bubbles will enter the inkjet cartridge and ink cannot be reliably supplied. In such a case, print quality will be degraded and thinning or the like will occur. Therefore, as the insertion stroke of the ink absorber increases, the conditions to be satisfied in the process of inserting the ink absorber become more severe.
An example of a method for solving this problem is described in Japanese Patent Laid-Open No. 8-224887 (corresponding to U.S. Pat. No. 5,839,595). This example is illustrated in FIGS. 11A and 11B. A first ink-absorber container 201 having a space for containing a first ink absorber 203 and a second ink-absorber container 202 having a space for containing a second ink absorber 204 are provided. The first ink-absorber container 201 and the second ink-absorber container 202 are connected to each other such that the first ink absorber 203 and the second ink absorber 204 come into contact with each other to form a contact area 205. In this structure, the ink-absorber containers are sectioned from each other at a suitable position. Therefore, an ink container having a long length in the height direction can be obtained without increasing the insertion stroke of the ink absorber.
However, in the structure described in Japanese Patent Laid-Open No. 8-224887 (corresponding to U.S. Pat. No. 5,839,595), the number of components is increased because two ink absorbers are used.
Accordingly, to reduce the number of components and costs, a structure in which a single ink absorber is contained in two containers, as shown in FIG. 12A, can be used. However, in this structure, as shown in FIG. 12B, an ink absorber 303 protrudes from wall surfaces of a first ink-absorber container 301 and a second ink-absorber container 302 at bonding portions thereof. If the ink absorber protrudes from the bonding portions, the ink absorber will be sandwiched between welding portions and weld failure will occur. As a result, weld reliability will be reduced.